9G THE APODOTJS HOLOTHURIANS 



ured in the posterior part of specimens from Trieste are from 350 to 500 /. 

 Ludwig further calls attention to the remarkable "giant" anchors, 700-950 p. 

 long, first figured by Woodward and Barrett ('58), with perfectly smooth arms, 

 which occur in the dorsal interradii of this species. I was unable to find any 

 in the specimens from Trieste, so that I am in doubt as to their value as a 

 specific character. 



LABIDOPLAX DTJBIA. 

 PLATE V, FIGS. 25 AND 28. 



Synapta dubia Semper, 1868, p. 10. Calcareous particles, pi. iv, fig. 11. 

 Synapta inccria Ludwig, 1874, p. 79. Calcareous particles, pi. vi, fig. 3. 

 Synapta incerta var. varlabilis Theel, 1886a, p. 14. Anchor-plates, pi. i, fig. 5. 

 Ldbidoplax dubia Ostergren, 1898&. 

 Ldbidoplax incerta Ostergren, 18986. 

 Ldbidoplax incerta Sluiter, 1901. 



LENGTH. 60-100 mm. Most of the reported specimens are fragments. 



COLOR. White, dirty- whitish, or reddish, or with a violet tinge; tentacles 

 yellowish. 



DISTRIBUTION. Reported from Bohol and Zebu, Philippines (Semper) ; 

 Banka, D. E. I. (Ludwig) ; Japan (Theel) ; and Dutch East Indies (Sluiter). 

 Apparently a rare tropical and subtropical East Indian species. 



REMARKS. Owing to the small amount and poor condition of the material 

 examined, there is room for difference of opinion as to the validity of Ludwig's 

 ('74) incerta, but the differences between his specimen and Semper's ('68) are 

 so slight (miliary granules) or are based on factors so variable in this genus 

 (serration of anchor arms) that I can see no sufficient reason for separating 

 the two, especially as Theel ('86<z) thinks them probably identical. The speci- 

 mens from Japan in the National Museum show conclusively that this is a 

 valid species and convince me that dubia and incerta are identical. I think it 

 possible that Semper ( '68) mistook the first beginning of anchor-plates for 

 miliary granules, but even if not, the. differences between his figures and Lud- 

 wig's ('74) are not important. In the Japanese specimens the miliary granules 

 are very scarce and are usually straight rods, but sometimes resemble Ludwig's 

 figure. The anchor-arms are commonly smooth, but often have one, two, or 

 three teeth, which are sometimes minute and sometimes conspicuous. The 

 plates are commonly quite symmetrical, with three small holes near the tip, the 

 middle one largest, and three, of about the same size, at the posterior end; be- 

 tween these two series are either two large, elongated holes side by side, or one 

 long one and the other divided transversely into two, or both are divided trans- 

 versely, making a group of four holes. The anchors measured 200-265 /* 

 long, with the arms 80-115 /" across, while the plates are 180-235 /x long 



